I have the building down this particular rda says that i need 6mm of cotton. I plan on buying pre-built 6mm cotton. Most of the sites I frequent only have 3mm in stock. I know the reason I need 6mm is because of the height of the coil. My question is can I buy pre-built 3mm cotton and just use two of them or should I look harder and get 6mm pre-built? The rda I'm going to purchase is a Wotofo x MR.JustRight1 Profile 24mm Mesh rda.